1. Field of the Invention
The invention pertains to a linear drive, especially to a spindle drive. The invention also pertains to an adjustable unit with a linear drive.
2. Background Information
Various linear drives are known generally from the prior art. A lifting device is known from DE 2920133 B1 with at least two threaded spindles, which extend outward from each other in telescoping fashion and cooperate with rotatable nuts, which can be shifted in their positions along the threaded spindles. A first threaded spindle is driven, wherein the second threaded spindle is driven by the first threaded spindle, which acts by way of a slideway, the second threaded spindle being supported on the first threaded spindle. The two threaded spindles, which, when in their retracted state, extend essentially over the entire length of the lifting device, are arranged directly inside each other, wherein the threaded spindles are connected to each other by a tongue-and-groove guide or by a multi-cornered ring guide so that they are free to move (shift) in the axial direction but are unable to rotate with respect to each other.
The lifting device is relatively complex in design and requires a large number of parts. In addition, the device is driven exclusively by way of the first threaded spindle.